The present invention relates generally to computer systems and, more particularly, to a method for operating a serial test bus incorporated into a computer system including multiple modules interconnected to one another through at least one system bus to perform intermodule testing of the computer system across the system bus.
Computer systems constructed by interconnecting multiple modules for communication with one another over a system bus are well known in the art. Testing of these systems has of course been performed to determine whether any system faults result in erroneous communications between the modules. Such testing has been functional in that the working relationships between the various modules has been employed. For functional testing, signals stimulating various functions are written to the modules and their characteristic responses are monitored to determine proper operation of the modules.
Unfortunately, while some modules and signals are easy to test by means of functional testing, others are very difficult. For example, a memory module is easily tested by writing known data into the module, reading the data which was written and then restoring the memory. On the other hand, signals such as error signals generated by modules as the result of failures within the modules are very difficult to test. As a result, while intermodule testing over an interconnecting system bus has been performed, due to deficiencies in existing intermodule testing arrangements, such tests are typically not regularly performed.
Accordingly, there is a need for an improved intermodule test arrangement which will reliably test all connections between modules of multiple module computer systems. Preferably, an improved intermodule test arrangement would not require substantial additions to a computer system and would permit regular periodic testing of a computer system such that faulty interconnections between modules could be quickly detected and corrected leading to increased overall availability of the corresponding computer system.